AXPZ20 KNHC 172112

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2112 UTC Wed Jan 17 2018

Tropical Weather Discussion for the eastern Pacific Ocean from the Equator to 32N, east of 140W. The following information is based on satellite imagery, weather observations, radar, and meteorological analysis.

Based on 1800 UTC surface analysis and satellite imagery through 2100 UTC.


Gulf of Tehuantepec Gale Warning: Strong high pressure continues to build southward across eastern Mexico and the western Gulf of Mexico supporting a tight pressure gradient across the area. Gale force winds will continue to pulse from minimal to strong gale force, with the strongest winds expected during the late night and early morning hours. Winds are expected to gradually diminish below gale force by Friday afternoon. The resultant plume of northerly swell will continue to propagate well southward of the offshore Gulf of Tehuantepec waters, mixing with long period NW swell. Seas will be up to 14 to 19 ft during the strongest winds, gradually subsiding by the end of the week as the winds diminish.


A surface trough axis extends from 08N77W to low pressure near 06N79W to 06N84W to 05N93W. The intertropical convergence zone axis extends from 05N93W to 07N106W to 06N115W to 09N135W, then resumes from 09N139W to 09N140W. Scattered moderate convection is within 120 nm in the SW semicircle of the low, and within 45 nm either side of the ITCZ axis between 104W and 115W. Scattered moderate and isolated strong convection is within an area bounded by 12N140W to 16N128W to 11N115W to 04N115W to 04N126W to 08N133W to 06N140W to 12N140W.



Please see the special features section for information about the ongoing gale warning in the offshore waters of the Gulf of Tehuantepec.

In the Gulf of California, light to moderate NW flow is forecast across across the entire gulf waters through Friday afternoon. Winds will become southerly Friday evening ahead of a cold front, increasing to fresh to strong in the northern gulf Friday night, then shifting to NW to N behind the front. The front will dissipate while it moves southward across the gulf during the day Saturday with mainly moderate to fresh northerly flow in its wake for the end of the weekend, except increasing to fresh to strong in the central and southern Gulf Sunday afternoon and night as the pressure gradient tightens across that area.

Elsewhere across the offshore waters of Mexico, large NW swell continues to propagate SE across the waters, with seas of 8-12 ft prevailing, except 5-8 ft between 98W and 105W. The large swell is generating high and powerful surf along the coasts and outer reefs of the Baja California peninsula and mainland Mexico which will continue this evening, with coastal flooding also possible. Another pulse of NW swell will reach the offshore waters off Baja California Norte Thursday night. Seas will peak near 13-15 ft by Friday, while seas of 12 ft or greater will spread across the offshore waters off the entire length of the Baja Peninsula through the upcoming weekend.


Fresh NE gap winds winds will pulse to strong each night and early morning across the Gulf of Papagayo through Saturday morning, diminishing thereafter. Winds will also pulse to fresh to strong offshore of other Central America gulfs and gap wind areas tonight into early Thursday. Elsewhere, mainly light to gentle offshore winds will prevail N of 09N, with light to gentle southerly flow S of 09N. NW swell originating from a gale force wind event in the Gulf of Tehuantepec along with longer period NW swell will arrive across the area waters Thursday and Friday, building seas offshore to 5-7 ft.


Large, long period NW swell continues to propagate SE across the forecast waters, with seas of 8 to 14 ft across the waters W of 95W-100W. A weakening cold front currently W of the area will move SE of 30N140W by early Thursday, then will get reinforced by building high pressure Thursday evening. Winds W of the reinforced front will increase to fresh to strong Thursday evening, with fresh to strong trades gradually spreading across the waters N of 10N W of 110W during the upcoming weekend while the front also dissipates across the N central waters.

$$ Lewitsky